How difficult would it be to rotate a steam radiator 90 degrees so i can get an extra 2-3 feet of space for kitchen counters. so once it is all finished the radiator is perpendicular to the wall at the end of the cabinets.

It's probably not going to work too well because the inlet or outlet is still the space you plan to occupy. The radiator can be turned but, you will have to extend the inlet/outlet to reach the new location.